JDK自带的有趣的例子

Pattern p = Pattern.compile("cat\\b");
		Matcher m = p.matcher("one cat two cats in the yard");
		StringBuffer sb = new StringBuffer();
		while (m.find()) {
			m.appendReplacement(sb,"dog");
		}
		m.appendTail(sb);
		System.out.println(sb.toString());

自己加个字边界匹配，sb出来以后更好理解